I like to check it out before I use it, and I'm glad I did. Filter comes with replaceable cartridge installed, with a plastic bag around it. There was nothing in the instructions about removing the bag before use. Other than that, I think it's a 5 star deal. You will need USB power. I love it. Only one other thing, when you try to open don't force it to open try the other way, the arrows are confusing.